Experimental dataset from a round robin test of contact parameters and hysteresis loops for nonlinear dynamic analysis.

This data article describes the extensive experimental dataset of friction hysteresis measured during the round robin test of the original research article [1]. The round robin test was performed on the two different fretting rigs of Imperial College London and Politecnico di Torino, and consisted of recording comparable friction hysteresis loops on specimen pairs manufactured from the same batch of raw stainless steel. The reciprocating motion of the specimens was performed at room temperature under a wide range of test conditions, including different normal loads, displacement amplitudes, nominal areas of contact and excitation frequencies of 100 Hz and 175 Hz. Friction forces and tangential relative displacements for each specimen pair were recorded and stored as hysteresis raw data. Each hysteresis loop was post-processed to extract friction coefficient, tangential contact stiffness and energy dissipated, whose evolution with wear was thus obtained and stored as well. MATLABⓇ scripts for post-processing and plotting data are included too. The dataset can be used by researchers as a benchmark to validate theoretical models or numerical simulations of friction hysteresis models and wear mechanisms, and also to study the physics of friction hysteresis and its contact parameters. This friction data can also be used as input in models for nonlinear dynamics applications as well as to provide information on the contact measurement uncertainty under fretting motion. Other applications include using this data as a training set for machine learning applications or data-driven models, as well as supporting grant applications.

Comparing Cyclic Fatigue Resistance and Free Recovery Transformation Temperature of NiTi Endodontic Single-File Systems Using a Novel Testing Setup.

The aim of this study was to assess the effect of body temperature (37 °C) on the cyclic fatigue resistance of three endodontic single-file systems using a new testing setup. One Shape® new generation (OS), WaveOne™ (WO) and WaveOne® GOLD (WOG), which are made from different NiTi alloys and operated in different motions (rotation/reciprocation), were evaluated. The study design included four groups. Each group comprised 30 files, 10 files of each of the three file systems, tested at 20 ± 2 °C (group 1 and 3) and at 37 ± 1 °C (group 2 and 4). All files were tested in a custom-made metal block with artificial canals of 60° angle, and a 5 mm and 3 mm radius of curvature, respectively. A heating element was attached to replicate a temperature of 37 °C. Files were introduced 18 mm into the canals and operated until failure. Transformation temperatures of five samples of each of the tested file systems were determined via the bend and free recovery (BFR) method. With the exception of WOG in canals with a 3 mm radius of curvature (p = 0.075), all the tested file systems showed statistically significantly less time needed to fracture when operated at 37 ± 1 °C compared to at 20 ± 2 °C in canals with a 5 mm and 3 mm radius of curvature using Mann-Whitney U test (p < 0.05). All file systems showed transformation temperatures below the body temperature. We concluded that body temperature directly affects the cyclic fatigue resistance of all tested file systems. Bend and free recovery can be suitable for the determination of austenite finish temperatures (Af) of endodontic instruments as it allows testing a longer portion of the instrument.

Comparative Evaluation of Debris Expulsion Beyond Apex During Re-root Canal Treatment by Utilizing Two Re-treatment Rotary Files and Two Reciprocating Files: An In-Vitro Study.

AIM: This study aimed to assess and compare debris quality expelled beyond the apex during re-treatment using two reciprocating and two re-treatment rotary files. MATERIALS AND METHODS: A total of 80 healthy human mandibular premolars excised for orthodontic therapy were selected. Distilled water was used to sterilize the teeth before they were preserved. The canals were widened and coronal access was created so that the F2 ProTaper universal system could be used. For the obturation, we utilized gutta-percha cones and AH plus sealant. All samples were cone-beam computed tomography (CBCT) recorded. Teeth were separated into four groups (n=20); Group 1: ProTaper re-treatment, Group 2: Mtwo re-treatment, Group 3: WaveOne gold, and Group 4: Reciproc. The re-instrumented process included collecting the extruded debris in Eppendorf tubes and then drying it off by evaporating the distilled water. The weight of the tube with debris was subtracted from the weight of the tube without debris to get the dry debris weight. Post-retreatment CBCT was recorded for all samples. Mean apical debris extrusion values were obtained, after which necessary statistical analysis was obtained using SPSS Statistics, version 21 (IBM Corp., Armonk, NY) to obtain the results. A one-way analysis of variance (ANOVA) and the student t-test were utilized for statistical analysis to compare the different experimental groups. Post-hoc Bonferroni tests were used to compare several groups. RESULT: No statistical difference (p>0.05) was identified in the filler material that was left over across all groups. The reciprocating files discharged more material compared with re-treatment file systems. CONCLUSION: The Reciproc files expelled more waste than WaveOne gold, ProTaper re-treatment, and Mtwo re-treatment file systems. Reciprocating file systems showed better cleaning efficiency compared to the re-treatment file systems.

Coexistence of a Classical Nodoventricular Accessory Pathway With a Left-Sided Mahaim Accessory Pathway.

The coexistence of 2 Mahaim pathways represents a diagnostic challenge. We present a case in which the SH/HA intervals were useful for identifying concealed nodoventricular or His-ventricular pathways.

Investigation of clinical significance of ST-segment depression during paroxysmal supraventricular tachycardia.

INTRODUCTION: There are great differences in ST-segment depression during PSVT episodes. The aim of this study is to investigate the clinical significance of ST segment depression during PSVT. METHODS: The study enrolled 333 consecutive patients who were diagnosed with PSVT by electrophysiological test from Jan 1, 2021 to July 31, 2022. The range, magnitude and morphology of ST-segment depression were described. The correlation between ST-segment depression and symptoms of chest tightness, chest pain or hypotension, the correlation between ST-segment depression and coronary stenosis, and the possible influencing factors were analyzed. In addition, the diagnostic efficacy of ST-segment depression for AVRT was determined. RESULTS: ST-segment depression was present in 85% of patients, in 70% of which the depression range was more than six leads. The magnitude of the depression was more significant in precordial leads (P < 0.001). ST-segment depression of >1 mm in limb leads and precordial leads was found in 36.0% and 49.8% of the patients, respectively, while >3 mm was found in 2.4% and 9.6%, respectively. The morphology of ST-segment depression in limb leads was different from that in precordial leads (P < 0.001). Downsloping ST-segment depression was more common in limb leads (limb vs. precordial: 40.5% vs. 12.6%), whereas upsloping depression was more common in precordial leads (limb vs. precordial: 3.0% vs. 23.1%). Correlation analysis showed that ST-segment depression was not correlated with symptoms of chest tightness and pain, nor was it correlated with coronary artery stenosis. The most important influencing factor is the type of PSVT, especially affecting the morphology of depression in limb leads (OR = 10.27 [5.93-17.79], P < 0.001). The sensitivity and specificity of downsloping ST-segment depression in limb leads for diagnosis of AVRT were 75.5% and 76.7%. CONCLUSION: ST-segment depression is a common ECG change during PSVT episodes, and it's not associated with severe coronary stenosis. The type of PSVT has a significant effect on the manifestation of ST-segment depression. The downslope morphology of ST-segment depression in limb leads is helpful in differentiating AVRT from AVNRT.

Orthodromic Reciprocating Tachycardia Relying on Aberrant Conduction: The Need for a Larger Circuit.

Aberrant conduction during orthodromic reciprocating tachycardia (ORT) prolongs the ventriculoatrial conduction time, which can be essential for the maintenance of tachycardia in specific cases. We searched for ORT relying on aberrancy among 220 cases in our center. Three patients showed the phenomenon of aberrancy-dependent ORT. All accessory pathways were located at the lateral regions of the atrioventricular annulus. None of them had a baseline bundle branch block (BBB). Creating a functional BBB was necessary to induce the tachycardias. In two cases, termination of tachycardias was directly associated with resolution of the aberration. In the other case, re-entry required both BBB and slow pathway conduction. We conclude that extra transseptal time caused by aberrancy can be an integral part of the ORT circuit, which explains the infrequent and unsustainable episodes of ORT in certain patients and is useful in understanding the circuit and localizing the pathway.

Shaping Efficiency of Rotary and Reciprocating Kinematics of Engine-driven Nickel-Titanium Instruments in Moderate and Severely curved Root Canals Using Microcomputed Tomography: A Systematic Review of Ex Vivo Studies.

INTRODUCTION: This systematic review aimed to compare reciprocating with continuous rotary instrumentation kinematics, by means of microcomputed tomography evaluations, in extracted human permanent teeth with moderate and severe canal curvatures. METHODS: The research protocol was registered in the International Prospective Register of Systematic Reviews and given the reference number CRD42023404035. An electronic search was undertaken in MEDLINE (PubMed), EBSCO, Scopus, Web of Science databases until December 2021. Manual screening of issues in endodontic journals and references of relevant articles were assessed individually. The risk of bias (RoB) of the included articles was evaluated with the QUIN tool (Quality Assessment Tool for In Vitro Studies). RESULTS: Among 1640 retrieved articles, 49 were included in the qualitative synthesis. Fifteen articles had low RoB, 33 articles had medium RoB, and only 1 study was at high RoB. Continuous rotary systems had better centering ability in both moderate and severe canal curvatures and resulted in less apical transportation in severely curved root canals. None of the kinematic systems was capable of instrumenting the entire canal surface area. Reciprocating kinematics systems tended to provide higher increase in surface area of severely curved canals and produced fewer dentinal microcracks in moderately curved canals. CONCLUSIONS: The evidence presented in this review suggests that continuous rotary system seems to be better than reciprocating system in solving the major issues encountered during root canal instrumentation of extracted teeth with moderate and severe curvatures.

Self-propelled object that generates a boundary with amphiphiles at an air/aqueous interface.

A benzoic acid (BA) disk was investigated as a novel self-propelled object whose driving force was the difference in surface tension. 4-Stearoyl amidobenzoic acid (SABA) was synthesized as an amphiphile to control the nature of motion based on intermolecular interactions between BA and SABA. The BA disk exhibited characteristic motion depending on the surface density of the SABA on the aqueous phase, that is, reciprocating motion as a one-dimensional motion and restricted and unrestricted motion as a two-dimensional motion. The trajectory of the reciprocating motion was determined by the initial direction of motion, and the boundary between an aqueous surface and the BA-SABA condensed molecular layer was used as the field's boundary. The presented results indicate that the characteristic nature of motion can be designed at the molecular level based on the intermolecular interactions between an energy-source molecule and an amphiphile.

Response to spontaneous and induced His refractory ventricular premature beats during long RP tachycardia: What is the mechanism?

This electrophysiology tracing demonstrates a graded postexcitation response of the retrograde limb of an orthodromic reentrant tachycardia circuit with varying His refractory VPB coupling intervals, which reiterates the decrementally conducting retrograde limb of the tachycardia circuit.

Cyclic Fatigue of Different Reciprocating Endodontic Instruments Using Matching Artificial Root Canals at Body Temperature In Vitro.

Reciprocating motion expands the lifetime of endodontic instruments during the preparation of severely curved root canals. This study aimed to investigate the time to fracture (TTF) and number of cycles to failure (NCF) of different reciprocating instruments (n = 20 in each group) at body temperature using a dynamic testing model (amplitude = 3 mm). Reciproc Blue (RPB), size 25/.08, WaveOne Gold (WOG) 25/.07, Procodile (Proc) 25/.06, R-Motion (RM_06) 25/.06 and R-Motion (RM_04) 30/.04 instruments were tested in their specific reciprocating motion in artificial matching root canals (size of the instrument ± 0.02 mm; angle of curvature 60°, radius 5.0 mm, and centre of curvature 5.0 mm from apical endpoint). The number of fractured instruments, TTF, NCF, the and lengths of the fractured instruments were recorded and statistically analysed using the Chi-Square or Kruskal-Wallis test. Both TTF (median 720, 643, 562, 406, 254 s) and the NCF (3600, 3215, 2810, 2032, 1482 cycles) decreased in the following order RM_06 > RPB > RM_04 > Proc > WOG with partially significant differences. During testing, only six RM_06 instruments fractured, whereas 16/20 (RPB), 18/20 (Proc), and 20/20 (RM_04, WOG) fractures were recorded (p < 0.05). Within the limitations of the present study, blue-coloured RPB and RM instruments exhibited a significantly superior cyclic fatigue resistance compared to SE-NiTi and Gold-wire instruments. Heat treatment, cross-sectional design and core mass significantly influenced the longevity of reciprocating instruments in cyclic dynamic testing.

Multimethod analysis of large- and low-tapered single file reciprocating instruments: Design, metallurgy, mechanical performance, and irrigation flow.

AIM: To compare eight large- and low-tapered heat-treated reciprocating instruments regarding their design, metallurgy, mechanical properties, and irrigation flow through an in silico model. METHODOLOGY: A total of 472 new 25-mm E-Flex Rex (25/.04 and 25/.06), Excalibur (25/.05), Procodile (25/.06), Reciproc Blue R25 (25/.08v), WaveOne Gold Primary (25/.07v), and Univy Sense (25/.04 and 25/.06) instruments were evaluated regarding their design (stereomicroscopy, scanning electron microscopy, and 3D surface scanning), metallurgy (energy-dispersive X-ray spectroscopy and differential scanning calorimetry), and mechanical performance (cyclic fatigue, torsional resistance, cutting ability, bending and buckling resistance). Computational fluid dynamics assessment was also conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparations. Kruskal-Wallis and one-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%). RESULTS: Instruments presented variations in blade numbers, helical angles, and tip designs, with all featuring non-active tips, symmetrical blades, and equiatomic nickel-titanium ratios. Cross-sectional designs exhibited an S-shaped geometry, except for WaveOne Gold. Univy 25/.04 and Reciproc Blue displayed the smallest and largest core diameters at D3. Univy 25/.04 and E-Flex Rec 25/.04 demonstrated the longest time to fracture (p < .05). Reciproc Blue and Univy 25/.04 exhibited the highest and lowest torque to fracture, respectively (p < .05). Univy 25/.04 and Reciproc Blue had the highest rotation angles, whilst E-Flex Rec 25/.06 showed the lowest angle (p < .05). The better cutting ability was observed with E-Flex Rec 25/.06, Procodile, Excalibur, and Reciproc Blue (p > .05). Reciproc R25 and E-Flex Rec showed the highest buckling resistance values (p < .05), with WaveOne Gold being the least flexible instrument. The impact of instruments' size and taper on wall shear stress and apical pressure did not follow a distinct pattern, although Univy 25/.04 and E-Flex Rec 25/.06 yielded the highest and lowest values for both parameters, respectively. CONCLUSIONS: Low-tapered reciprocating instruments exhibit increased flexibility, higher time to fracture, and greater angles of rotation, coupled with reduced maximum bending loads and buckling strength compared to large-tapered instruments. Nevertheless, low-tapered systems also exhibit lower maximum torque to fracture and inferior cutting ability, contributing to a narrower apical canal enlargement that may compromise the penetration of irrigants in that region.

Successful high-resolution three-dimensional electroanatomical mapping and radiofrequency catheter ablation of a posteroseptal accessory pathway in a dog using CARTO 3.

A one-year-and-seven-month-old, 28 kg, male castrated crossbreed dog was presented for supraventricular tachycardia causing recurrent episodes of anorexia and lethargy. Sotalol (2.2 mg/kg q12 h) reduced the frequency of symptomatic episodes but did not provide full relief. Three-dimensional electroanatomical mapping was performed at the Ghent University Small Animal Teaching hospital using the CARTO 3. Right atrial activation mapping identified the earliest atrial activation right posteroseptal, near the tricuspid annulus. Fast retrograde ventriculoatrial conduction during tachycardia and extrastimulus testing confirmed the presence of a concealed right posteroseptal accessory pathway. Six radiofrequency catheter ablation applications were delivered, and tachycardia remained uninducible. The dog recovered well from the procedure. Sotalol was stopped three weeks later, and no more clinical signs were noted by the owner. Repeated 24-hour electrocardiography monitoring on day one and at one, three, and 12 months after the procedure showed no recurrence of tachycardia.

Scale-Fractal Detrended Fluctuation Analysis for Fault Diagnosis of a Centrifugal Pump and a Reciprocating Compressor.

Reciprocating compressors and centrifugal pumps are rotating machines used in industry, where fault detection is crucial for avoiding unnecessary and costly downtime. A novel method for fault classification in reciprocating compressors and multi-stage centrifugal pumps is proposed. In the feature extraction stage, raw vibration signals are processed using multi-fractal detrended fluctuation analysis (MFDFA) to extract features indicative of different types of faults. Such MFDFA features enable the training of machine learning models for classifying faults. Several classical machine learning models and a deep learning model corresponding to the convolutional neural network (CNN) are compared with respect to their classification accuracy. The cross-validation results show that all models are highly accurate for classifying the 13 types of faults in the centrifugal pump, the 17 valve faults, and the 13 multi-faults in the reciprocating compressor. The random forest subspace discriminant (RFSD) and the CNN model achieved the best results using MFDFA features calculated with quadratic approximations. The proposed method is a promising approach for fault classification in reciprocating compressors and multi-stage centrifugal pumps.

Impact of Sequential Use of Reciprocating Files on the Shaping Load During Root Canal Treatment.

INTRODUCTION: The purpose of this in vitro study was to investigate the apical and coronal loads generated during shaping canals with 2 successive reciprocating files in comparison to a single reciprocating file from the same system. METHODS: A total of 40 narrow and straight canals were distributed into two groups: R-Motion with single file (RMS) and R-Motion with multiple files (RMM). In both groups, the R-Motion system was used in a reciprocating motion. After establishing glide path, the RMS canals were shaped down to working length with a single file (25/.06) in two insertions while the RMM canals were shaped with two files (20/.04 and 25/.06) to the working length. The shaping time and effects of tested groups on the apical and coronal peak loads were statistically analyzed using the t-test and Mann-Whitney U test, respectively, at a 95% confidence level. RESULTS: All canals were completely shaped in three insertions and no file deformation or fracture was observed. The RMS and RMM were able to shape canals in 117.3 ± 15.1 and 123.7 ± 7.3 seconds, respectively (P < .05). Within each group, the shaping load appeared to increase with the successive insertions of the file. In both groups, the ranges of apical and coronal peak loads were 0.41-1.87 N and 0.38-1.03 N, respectively. The RMM and RMS had comparable apical and coronal peak loads (P > .05) except in the last insertion where RMM showed clearly lower apical peak load than RMS (P < .01). CONCLUSIONS: Under the current laboratory conditions using the R-Motion system, preshaping the canal with a smaller reciprocating file was shown to favorably reduce the apical peak loads induced during canal shaping of extracted teeth.

Intracanal removal and apical extrusion of filling material after retreatment using rotary or reciprocating instruments: A new approach using human cadavers.

AIM: This study compared intracanal removal of filling as well as the frequency and volume of extruded material after retreatment with either HyFlex or Reciproc instruments in mandibular teeth from cadavers. METHODOLOGY: The root canals of 14 pairs of contralateral single-rooted teeth in mandibles of cadavers were instrumented with Reciproc R40 and filled using lateral compaction. The mandibles were scanned in a micro-computed tomographic (micro-CT) device before and after retreatment procedures. The contralateral teeth were assigned to two groups (n = 14) according to the retreatment protocol using either HyFlex or Reciproc instrument systems. In the HyFlex group, the HyFlex Remover instrument was worked 3 mm short of the working length (WL), followed by HyFlex CM 40.04 and 50.04 at the WL. In the Reciproc group, the R50 instrument was worked up at the coronal two thirds, followed by two more cycles until the WL was reached. Pre- and post-operative micro-CT images were analysed for extrusion and intracanal removal of filling material. RESULTS: After retreatment, extrusion of filling material occurred in 11 (78%) and 14 (100%) teeth from HyFlex and Reciproc groups respectively (p > .05). A similar volume of extruded material was observed after retreatment with both systems (p > .05). A significant decrease in the intracanal filling volume was verified after retreatment with both tested systems (p < .05). However, residual filling material was found in all root canals, regardless of the system. The amount of filling material removed (HyFlex = 80.8%; Reciproc = 65.9%) and the operation time was similar between systems (p > .05). CONCLUSIONS: A high frequency of filling material extrusion was observed after retreatment with the two systems in a cadaver model, with no significant difference between them. Both protocols obtained similar efficacy in filling material removal procedures, although none completely cleaned the canals.

Evaluation of the Ability of 3 Reciprocating Instruments to Remove Obturation Material: A Micro-Computed Tomography Study.

INTRODUCTION: The purpose of this study was to evaluate the ability of the Reciproc, Reciproc Blue, and WaveOne Gold systems to remove filling material during endodontic retreatment of extracted human mandibular premolars. METHODS: Thirty-nine teeth were instrumented with the Protaper Universal System to the F3 file and filled with the Tagger hybrid technique using an F3 gutta-percha cone and AH Plus cement. At the end of this period, the teeth were scanned with micro-computed tomography before and after removal of the filling material from the root canals. The teeth were divided into 3 groups (n = 13) based on the apical volume, depending on the systems used to remove the filling material. Group GR: Reciproc 40/.06; Group GRB: Reciproc Blue 40/.06; and Group GWG: WaveOne Gold 35/.06. The results were statistically analyzed using the tests of Kruskal-Wallis, Duncan, and analysis of variance at a significance level of 5%. RESULTS: The results showed that there were no significant differences between the amounts of filling material removed, either for the apical and middle regions alone or in the overall evaluation for the 3 groups (P = .97). The time evaluation statistically showed that the GR and GWG groups required less time to clean the root canals than the GRB group. CONCLUSIONS: Reciproc R40 files and WaveOne Gold Medium files required less time for endodontic treatment than Reciproc Blue R40 files. There was no difference in the ability to remove obturation material between the 3 instruments. No instrument was able to completely remove the filling material from the root canals.

Catheter ablation for an incessant arrhythmia in a preterm low-weight neonate.

A 15-day-old neonate weighing 1800 g presented with incessant long-RP tachycardia. Temporary cessation of the arrhythmia with adenosine confirmed the diagnosis of permanent junctional reciprocating tachycardia (PJRT). The arrhythmia was refractory to multiple drugs. An electrophysiological study confirmed diagnosis. The arrhythmia was successfully treated with radiofrequency. Learning objective: Transcatheter radiofrequency ablation can be done safely in infants who are unresponsive to medical therapy, regardless of age and body weight.

A unique location of the accessory pathway in a child with permanent junctional reciprocating tachycardia.

Permanent junctional reciprocating tachycardia (PJRT) is a rare supra ventricular tachycardia (SVT) due to an accessory pathway (AP), characterized by slow and decremental retrograde conduction, which is predominantly seen in infants and children. Although the typical site of AP in PJRT is a right posteroseptal region around or just within the coronary sinus (CS), atypical sites of AP have been described. We report a rare case of PJRT in a 7-year-old girl with an AP located in the superio-paraseptal (Para-Hsian) region that was successfully ablated through a non-coronary sinus.